Polymeric malonic acid derivatives

ABSTRACT

Polymers or oligometic compounds of the general formula ##STR1## in which X, X a  and X b  are an ester, amide or cyano group, Y, Y a  and Y b  are --O-- or --NR 10  --, R 1 , R 1a  and R 1b  are a group which contains a polyalkylpiperidine radical, and R 1a  can also be alkyl, and R 3 , R 3a  and R 3b  are alkylene, alkenylene, arylene-dialkylene, cycloalkylene-dialkylene or monooxa-alkylene or polyoxa-alkylene, can be prepared by the polycondensation of malonic acid esters or amides or cyanoacetic acid esters or amides with difunctional compounds, preferably dihalogen compounds, in the presence of bases. The products obtained have a molecular weight of 800 to 20,000 and are outstanding light stabilizers for organic polymers.

The invention relates to polyalkylpiperidine derivatives of polymeric oroligomeric malonic acids, which are light stabilisers for organicpolymers, and also to the polymers stabilised with these compounds.

It is known that sterically hindered 2,2,6,6-tetraalkylpiperidines andtheir derivatives are excellent light stabilisers for organic materials,in particular for organic polymers. Polyalkylpiperidinyl esters ofsubstituted malonic acids, for example of dibenzylmalonic acid, havealso already been proposed as light stabilizers (GermanOffenlegungsschrift No. 2,718,458). Corresponding esters of substitutedcyanoacetic acids, for example of dibenzylcyanoacetic acid, have beenproposed in German Offenlegungsschrift No. 2,755,340.

It is furthermore known that such polyalkylpiperidine light stabiliserslose their action as a result of migration or extraction from thesubstrate to be stabilised, and attempts have been made to extend theperiod of action of such light stabilisers by increasing their molecularweight. Malonic acid derivatives of these polymeric or oligomericpiperidine light stabilisers have also already been disclosed. Thus, forexample, Example 15 of German Offenlegungsschrift No. 2,719,131describes the preparation of a polyester of the formula ##STR2## whichis then converted to a polyester of the formula ##STR3## by reactionwith N-(3,5-di-tert.-butyl-4-hydroxybenzyl)dimethylamine.

Such polyesters are outstanding stabilisers which have a long-lastingstabilising action provided they are not subjected to the effects ofhydrolysis. Under conditions of hydrolysis, however, they are rapidlydegraded to give low-molecular fragments, which no longer have the saidadvantages of the polymeric light stabilisers.

The object of the present invention was therefore to find polymeric oroligomeric polyalkylpiperidine derivatives of malonic acids, which areinsensitive or less sensitive to hydrolysis. It has been found thatpolymalonic acid derivatives can be prepared, of which the main polymerchain does not contain any hydrolysable groups, of which the side chainscannot easily be hydrolysed, and which constitute excellent lightstabilisers for organic polymers.

The invention therefore relates to polymers or oligomeric compounds ofthe general formula I ##STR4## and their salts, in which X is--CO--Y--R² or --CN, X^(a) is --CO--Y^(a) --R^(2a) or --CN, and X^(b) is--CO--Y^(b) --R^(2b) or --CN, Y, Y^(a) and Y^(b) independently of oneanother are --O-- or --NR¹⁰ --, R¹, R^(1a) and R^(1b) independently ofone another are a group of the formulae II, III, IV, V or VI ##STR5##and R^(1a) is also C₁ -C₁₈ -alkyl, R² is identical to R¹ or is H, C₁-C₁₈ -alkyl, C₃ -C₇ -alkenyl or C₇ -C₁₁ -aralkyl, R^(2a) is identical toR^(1a) or is H, C₁ -C₁₈ -alkyl, C₃ --C₇ -alkenyl or C₇ -C₁₁ -aralkyl,and R^(2b) is identical to R^(1b) or is H, C₁ -C₁₈ -alkyl, C₃ -C₇-alkenyl or C₇ -C₁₁ -aralkyl, R³, R^(3a) and R^(3b) independently of oneanother are C₂ -C₃₆ -alkylene, C₄ -C₁₈ -alkenylene, C₈ -C₂₀-arylene-dialkylene, C₈ -C₁₂ -cycloalkylenedialkylene or C₄ -C₂₀-monooxa-alkylene or polyoxa-alkylene, R⁴ is hydrogen, C₁ -C₁₈ -alkyl,C₃ -C₁₈ -alkenyl, C₃ -C₅ -alkynyl, C₂ -C₁₈ -alkanoyl, C₃ -C₅ -alkenoyl,benzoyl, unsubstituted or C₁ -C₄ -alkyl-substituted C₇ -C₁₁ -aralkyl,cyanomethyl, a group --CH₂ --CH(OH)--R⁶, OH, O.(oxyl oxygen), --COOC₁-C₄ -alkyl or --CON(R¹²)(R¹³), R⁵ is hydrogen or C₁ -C₄ -alkyl, R⁶ ishydrogen, C₁ -C₄ -alkyl, phenyl, C₁ -C₄ -alkoxy-methyl, phenoxymethyl orC₁ -C₄ -alkyl-phenoxymethyl, R⁷ is hydrogen, C₁ -C₁₈ -alkyl, C₃ -C₁₈-alkenyl, C₃ -C₅ -alkynyl, C₂ -C₁₈ -alkanoyl, C₃ -C₅ -alkenoyl,unsubstituted or C₁ -C₄ -alkyl-substituted C₇ -C₁₁ -aralkyl, O. orcyanomethyl, R⁸ is C₁ -C₁₈ -alkyl, C₃ -C₁₈ -alkenyl, C₃ -C₅ -alkynyl orC₇ -C₁₁ -aralkyl, R⁹ has one of the definitions given for R⁷, R¹⁰ ishydrogen, C₁ -C₁₈ -alkyl, C₃ -C₁₂ -alkenyl, cyclohexyl or unsubstitutedor C₁ -C₄ -alkyl-substituted C₇ -C₁₁ -aralkyl or C₆ -C₁₂ -aryl, R¹¹ ishydrogen or C₂ -C₄ -alkyl, R¹² is C₁ -C₁₂ -alkyl, C₃ -C₅ -alkenyl, C₅-C₈ -cycloalkyl, phenyl or benzyl, and R¹³ is hydrogen, C₁ -C₁₂ -alkyl,C₃ -C₅ -alkenyl, C₅ -C₈ -cycloalkyl or benzyl, or R¹² and R¹³, togetherwith the N atom to which they are bonded, form a 5-7-memberedheterocyclic ring, m, n and o independently of one another are zero or anumber from 1 to about 100, the sum of m+n+o being at least 3, and p iszero or 1.

Alkyl R², R^(2a), R^(2b), R⁴, R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ can beunbranched or branched alkyl groups. Examples of these are methyl,ethyl, propyl, isopropyl, butyl, sec.-butyl, tert.-butyl, isopentyl,n-hexyl, n-octyl, 2-ethylhexyl, n-decyl, n-dodecyl, n-hexadecyl orn-octadecyl.

Within the limits of the number of C atoms defined, alkenyl R², R^(2a),R^(2b), R⁴, R⁷, R⁸, R⁹, R¹⁰, R¹² and R¹³ can be, for example, allyl,methallyl, dimethylallyl, hexenyl, decenyl or oleyl.

Alkynyl R⁴, R⁷, R⁸ and R⁹ can be, for example, propargyl, but-2-yn-1-ylor pent-2-yn-1-yl. The preferred alkynyl is propargyl.

Unsubstituted or lower alkyl-substituted aralkyl R², R^(2a), R^(2b), R⁴,R⁷, R⁸, R⁹ and R¹⁰ can be, for example, benzyl, phenylethyl,phenylbutyl, naphthylmethyl, tolylmethyl, 4-tert.-butylbenzyl orxylylmethyl. Benzyl is preferred.

Alkanoyl or alkenoyl R⁴, R⁷ and R⁹ can be, for example, acetyl,propionyl, butyroyl, acryloyl, methacryloyl, hexanoyl, lauroyl orstearoyl. Acetyl and acryloyl are preferred.

Alkylene R³, R^(3a) and R^(3b) can be, for example, ethylene,1,3-propylene, 1,4-butylene, 1,6-hexylene, 2,2-dimethyl-1,3-propylene,1,8-octylene, 1,12-dodecylene or 1,20-eicosylene. Alkenylene R³, R^(3a)and R^(3b) can be, for example, 1,4-but-2-enylene,2-methyl-1,4-but-2-enylene, 1,6-hex-3-enylene or 1,8-oct-2-enylene.Arylenedialkylene or cycloalkylene-dialkylene R³, R^(3a) and R^(3b) canbe, for example, xylylene (phenylene-dimethylene), phenylene-diethylene,diphenyl-4,4'-dimethylene, naphthalene-1,4-dimethylene,cyclohexane-1,4-dimethylene or 2-methylcyclohexane-1,4-dimethylene.Monooxaalkylene or polyoxaalkylene R³, R^(3a) and R^(3b) can be, forexample, 3-oxa-1,5-pentylene, 3,6-dioxa-1,8-octylene or3,8-dioxa-1,10-decylene. R³, R^(3a) and R^(3b) are preferably C₆ -C₁₂-alkylene, butenylene, xylylene or cyclohexane-1,4-dimethylene.

The radical --N(R¹²)(R¹³) can be a primary or secondary, open-chain orcyclic amino radical, for example dimethylamino, butylamino,diethylamino, dibutylamino, dodecylamino, anilino, cyclohexylamino,methyl-cyclohexylamino, benzylamino, butyl-benzylamino, dibenzylamino,piperidino or morpholino.

If the radicals R⁴, R⁷ and R⁹ are not acyl radicals, the compounds ofthe formula I are capable of forming salts with acids. Examples of acidssuitable for this purpose are hydrochloric acid, phosphoric acid,methanesulfonic acid or phenylphosphonic acid. If the radicals X, X^(a)or X^(b) are --COOH, the compounds of the formula I can also form saltswith bases. Examples of these are, in particular, the alkali metalsalts.

The preferred compounds of the formula I are those in which m and n arezero or a number from 1 to 30 and o is zero, the sum of m+n being atleast 3, X is --CO--Y--R² and X^(a) is --CO--Y^(a) --R^(2a), Y and Y^(a)are --O-- or --NR¹⁰ --, R¹ and R^(1a) are a group of the formula II,III, IV or V, R² is identical to R¹ or is C₁ -C₆ -alkyl, and R^(2a) isidentical to R^(1a) or is C₁ -C₆ -alkyl, R³ and R^(3a) are C₂ -C₁₈-alkylene, C₄ -C₁₂ -alkenylene, C₈ -C₁₇ -arylene-dialkylene, C₈ -C₁₀-cycloalkylene-dialkylene or C₄ -C₈ -monooxaalkylene or C₄ -C₈-polyoxaalkylene, R⁴ is hydrogen, C₁ -C₆ -alkyl, C₃ -C₅ -alkenyl,propargyl, C₂ -C₅ -alkanoyl, C₃ -C₅ -alkenoyl or C₇ -C₁₁ -aralkyl, R⁵ ishydrogen, R⁶ is hydrogen, C₁ -C₂ -alkyl, phenyl or phenoxymethyl, R⁷ hasone of the definitions given for R⁴, R⁸ is C₁ -C₁₂ -alkyl, C₃ -C₅-alkenyl or C₇ -C₁₁ -aralkyl, R⁹ has one of the definitions given forR⁴, and R.sup. 10 is hydrogen, C₁ -C₁₂ -alkyl, benzyl or cyclohexyl.

Particularly preferred compounds of the formula I are those in which mis 3-20, n and o are zero, X is --CO--Y--R² and Y is --O-- or --NR¹⁰ --,R¹ and R² are a group of the formula II, R³ is C₆ -C₁₂ -alkylene,1,4-but-2-enylene, xylylene or cyclohexane-1,4-dimethylene, R⁴ ishydrogen, C₁ -C₄ -alkyl, allyl, benzyl or acetyl, R⁵ is hydrogen and R¹⁰is hydrogen, C₁ -C₁₂ -alkyl, benzyl or cyclohexyl.

The compounds of the formula I can be prepared by the polycondensationof malonic acid derivatives of the formula VII with difunctionalcompounds of the formula VIII, in the presence of at leaststoichiometric amounts of a base: ##STR6## Z is a nucleophilic leavinggroup, preferably halogen. Examples of difunctional compounds of theformula VIII are: ethylene dibromide, ethylene diiodide,1,6-dibromohexane, 1,8-dibromooctane,1,12-di-(p-toluenesulfonyloxy)-dodecane, 1,12-dibromododecane,1,4-dichlorobut-2-ene, m-xylylene dichloride, p-xylylene dichloride,di-(2-chloroethyl)ether, 1,4-di-(bromomethyl)-cyclohexane or1,4-di-(2-chloroethyl)-benzene.

The preferred aliphatic dihalides are those which have more than 5 C.atoms in the chain between the halogen atoms. This is in order to avoidside-reactions (the formation of cyclic malonic acid ester compounds) asmuch as possible during the polycondensation.

In the case of the above equation, only one compound of the formula VIIand only one compound of the formula VIII are reacted, so that ahomopolymeric compound of the formula I is formed in which n and o arezero. However, it is also possible to use a mixture of several differentcompounds of the formula VII or several different compounds of theformula VIII, in which case copolymeric compounds of the formula I areobtained which have different substituents X, X^(a), X^(b) or --Y--R¹,--Y^(a) --R^(1a), --Y^(b) --R^(1b), or different linkages R³, R^(3a),R^(3b), in the same macromolecule. Such copolymers can be randomcopolymers or block copolymers. However, the homopolymeric compounds arepreferred.

The components VII and VIII are used in approximately stoichiometricproportions. A small excess of component VII can be advantageous if itis desired to obtain products of relatively low molecular weight andwith a low content of end groups Z of the formula VIII. However, it isalso possible to carry out the polycondensation with a small excess ofcomponent VIII and to eliminate the end groups Z by after-treatment witha nucleophilic reagent, for example with an amine, an alkali metalalkoxide or an alkali metal hydride, or by after-treatment with a silvercompound, for example silver nitrate, silver hydroxide or moist silveroxide.

The polycondensation can be carried out without a solvent or in inertorganic solvents. Examples of suitable solvents are toluene, xylene,diethylene glycol dialkyl ethers or hydrogenated naphthalenes. Suitablebases are, in particular, alkali metal compounds, for example Na₂ CO₃,K₂ CO₃, NaOC₂ H₅, LiNH₂ or LiH. Quaternary ammonium hydroxides are alsosuitable. It is preferred to use alkali metal carbonates. The reactionis carried out at elevated temperature, preferably at 60°-160° C.

When using bases which are insoluble in the reaction mixture, thereaction is substantially facilitated by the addition of phase-transfercatalysts, for example quaternary ammonium salts, crown ethers ornon-cyclic neutral ligands such as polyethylene glycols and theirethers. Combinations of crown ethers and polyethylene glycols or theirethers are particularly effective, especially when using alkali metalcarbonates as the base.

Alternatively, the compounds of the formula I can be prepared by firstsubjecting a dialkyl malonate or an alkyl cyanoacetate to apolycondensation reaction with a compound of the formula VIII andreacting the product with an alcohol or an amine of the formula R¹ YH. Apolymer-analogous transesterification or amidation of this type can becarried out with the stoichiometric amount (or an excess) of R¹ YH orwith less than the stoichiometric amount. In the latter case, only apartial reaction takes place and this gives a copolymer having alkylester groups and --CO--YR¹ -- groups next to one another. The reactioncan also be carried out, stepwise or simultaneously, with two or threedifferent reagents --R¹ YH, R^(1a) Y^(a) H, R^(1b) Y^(b) H-- wherebycopolymers of the formula I are again obtained.

These reactions can also be carried out in the absence or in thepresence of solvents. Examples of suitable solvents are toluene, xylene,decalin or tetralin. In the reaction with alcohols, catalysts, such asthose generally known for transesterification reactions, for examplemetal alcoholates, tetraalkyl orthotitanates and alkali metal amides,are preferably added. The reaction with amines can be accelerated bymeans of basic catalysts. Both types of reactions are carried out atelevated temperature, preferably at 120°-180° C., under inert gas.

The introduction of the substituents R⁴, R⁷ and R⁹ can also be carriedout by a polymer-analogous reaction of a pre-formed polymer of theformula I in which R⁴, R⁷ or R⁹ is hydrogen. The generally known methodsfor the N-substitution of secondary amines are used for this purpose.Thus, for example, alkyl, alkenyl, aralkyl or acyl radicals can beintroduced by means of the corresponding halogen compounds. Cyanomethylcan be introduced by reaction with CH₂ O/HCN, methyl by reaction withCH₂ O/HCOOH and the oxyl oxygen by reaction with peroxy compounds.

The molecular weight of the polymers of the formula I obtainable in thisway can be as much as 50,000. For their use as stabilisers for polymers,however, the molecular weight should be 800 to 20,000, preferably1,000-10,000 and particularly preferably 1,000-5,000.

The compounds of the formula I according to the invention are effectivelight stabilisers for organic polymers which are sensitive to light, inparticular to UV light. Examples of such light-sensitive polymers are:

1. Polymers of monoolefins and diolefins, for example polyethylene(which may be crosslinked), polypropylene, polyisobutylene,polybut-1-ene, polymethylpent-1-ene, polyisoprene or polybutadiene, andpolymers of cycloolefins, for example of cyclopentene or norbornene.

2. Mixtures of the polymers mentioned under (1), for example mixtures ofpolypropylene with polyethylene or with polyisobutylene.

3. Copolymers of monoolefins and diolefins with one another or withother vinyl monomers, for example ethylene/propylene copolymers,propylene/but-1-ene copolymers, propylene/isobutylene copolymers,ethylene/but-1-ene copolymers, propylene/butadiene copolymers,isobutylene/isoprene copolymers, ethylene/alkyl acrylate copolymers,ethylene/alkyl methacrylate copolymers, ethylene/vinyl acetatecopolymers or ethylene/acrylic acid copolymers and their salts(ionomers), and terpolymers of ethylene with propylene and with a dienesuch as hexadiene, dicyclopentadiene or ethylidenenorbornene.

4. Polystyrene.

5. Copolymers of styrene or α-methylstyrene with dienes or acrylicderivatives, for example styrene/butadiene, styrene/acrylonitrile,styrene/ethyl methacrylate, styrene/butadiene/ethyl acrylate orstyrene/acrylonitrile/methyl acrylate; high impact strength mixtures ofstyrene copolymers and of another polymer, for example a polyacrylate, adiene polymer or an ethylene/propylene/diene terpolymer; and blockcopolymers of styrene, for example styrene/butadiene/styrene,styrene/isoprene/styrene, styrene/ethylene-butylene/styrene orstyrene/ethylene-propylene/styrene.

6. Graft copolymers of styrene, for example styrene grafted ontopolybutadiene, styrene and acrylonitrile grafted onto polybutadiene,styrene and maleic anhydride grafted onto polybutadiene, styrene andalkyl acrylates or alkyl methacrylates grafted onto polybutadiene,styrene and acrylonitrile grafted onto ethylene/propylene/dieneterpolymers, styrene and acrylonitrile grafted onto polyalkyl acrylatesor polyalkyl methacrylates, or styrene and acrylonitrile grafted ontoacrylate/butadiene copolymers, and their mixtures with the copolymersmentioned under (5), for example those known as so-called ABS, MBS, ASAor AES polymers.

7. Halogen-containing polymers, for example polychloroprene, chlorinatedrubber, chlorinated or chlorosulfonated polyethylene, or epichlorohydrinhomopolymers and copolymers, in particular polymers ofhalogen-containing vinyl compounds, for example polyvinyl chloride,polyvinylidene chloride, polyvinyl fluoride or polyvinylidene fluoride,and their copolymers such as vinyl chloride/vinylidene chloride, vinylchloride/vinyl acetate or vinylidene chloride/vinyl acetate.

8. Polymers derived from α,β-unsaturated acids and from theirderivatives, such as polyacrylates and polymethacrylates,polyacrylamides and polyacrylonitriles.

9. Copolymers of the monomers mentioned under (8) with one another orwith other unsaturated monomers, for example acrylonitrile/butadienecopolymers, acrylonitrile/alkyl acrylate copolymers,acrylonitrile/alkoxyalkyl acrylate copolymers, acrylonitrile/vinylhalide copolymers or acrylonitrile/alkyl methacrylate/butadieneterpolymers.

10. Polymers derived from unsaturated alcohols and amines or from theiracyl derivatives or acetals, such as polyvinyl alcohol, polyvinylacetate, stearate, benzoate or maleate, polyvinylbutyral, polyallylphthalate or polyallylmelamine.

11. Homopolymers and copolymers of cyclic ethers, such as polyalkyleneglycols, polyethylene oxide, polypropylene oxide or their copolymerswith bis-glycidyl ethers.

12. Polyacetals such as polyoxymethylene, and polyoxymethylenes whichcontain comonomers, for example ethylene oxide.

13. Polyphenylene oxides and sulfides.

14. Polyurethanes derived from polyethers, polyesters and polybutadieneswith terminal hydroxyl groups on the one hand and aliphatic or aromaticpolyisocyanates on the other hand, and their precursors(polyisocyanates, polyols and prepolymers).

15. Polyamides and copolyamides derived from diamines and dicarboxylicacids and/or from aminocarboxylic acids or the corresponding lactams,such as polyamide-4, polyamide-6, polyamide-6,6, polyamide-6,10,polyamide-11, polyamide-12, poly-2,4,4-trimethylhexamethyleneterephthalamide, poly-m-phenylene isophthalamide and their copolymerswith polyethers, for example with polyethylene glycol, polypropyleneglycol or polytetramethylene glycol.

16. Polyureas, polyimides and polyamide-imides.

17. Polyesters derived from dicarboxylic acids and diols and/or fromhydroxycarboxylic acids or the corresponding lactones, such aspolyethylene terephthalate, polybutylene terephthalate,poly-1,4-dimethylolcyclohexane terephthalate,poly-[2,2-bis-(4-hydroxyphenyl)-propane]terephthalate orpolyhydroxybenzoates, and block polyether-esters derived from polyetherswith hydroxyl end groups, dialcohols and dicarboxylic acids.

18. Polycarbonates.

19. Polysulfones and polyether-sulfones.

20. Crosslinked polymers derived from aldehydes on the one hand andphenols, urea or melamine on the other hand, such asphenol/formaldehyde, urea/formaldehyde and melamine/formaldehyde resins.

21. Drying and non-drying alkyd resins.

22. Unsaturated polyester resins derived from copolyesters of saturatedand unsaturated dicarboxylic acids with polyhydric alcohols, and vinylcompounds as crosslinking agents, and also their halogen-containing,slow-burning modifications.

23. Crosslinkable acrylic resins derived from substituted acrylic acidesters, for example from epoxyacrylates, urethane-acrylates orpolyester-acrylates.

24. Alkyd resins, polyester resins and acrylate resins crosslinked withmelamine resins, urea resins, polyisocyanates or epoxide resins.

25. Crosslinked epoxide resins derived from polyepoxides, for examplefrom bis-glycidyl ethers or from cycloaliphatic diepoxides.

26. Natural polymers such as cellulose, natural rubber and gelatine, andtheir derivatives chemically modified by a polymer-analogous reaction,such as cellulose acetates, propionates and butyrates, or the celluloseethers such as methylcellulose.

Of particular importance is the stabilisation of polyolefins, styrenepolymers, polyamides, polyurethanes and lacquering resins such as alkyd,acrylic and polyester resins.

The stabilisers according to the invention are added to the polymers ina concentration of 0.01 to 5% by weight, based on the material to bestabilised. Preferably, 0.1 to 2% by weight of the compounds, based onthe material to be stabilised, is incorporated into the latter.

The incorporation can be carried out before, during or after thepolymerisation, for example by mixing the compounds, and, ifappropriate, further additives, into the melt by the methods customaryin the art, before or during shaping, or by applying the dissolved ordispersed compounds to the polymer, if appropriate with subsequentevaporation of the solvent.

The stabilisers can also be added to the polymers to be stabilised inthe form of a master batch, which contains these compounds, for example,in a concentration of 2.5 to 25% by weight.

The invention therefore also relates to the polymers stabilised by theaddition of 0.01 to 5% by weight of a compound of the formula I, itbeing possible, if appropriate, for these polymers to contain furtherknown and customary additives. The polymers stabilised in this way canbe used in a wide variety of forms, for example as films, fibres, tapesor profiles or as binders for lacquers, adhesives or putties.

Examples of further additives together with which the stabilisers whichcan be used according to the invention can be employed are:

Antioxidants such as 2,6-dialkylphenols, alkylated hydroquinones,thio-bis-phenols, alkylidene-bis-phenols, O-, N- and S-hydroxybenzylcompounds, hydroxybenzylated malonic acid esters, hydroxybenzyl aromaticcompounds, hydroxybenzyl-s-triazines, amides and esters ofβ-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid, esters ofβ-(3,5-di-tert.-butyl-4-hydroxy-3-methylphenyl)-propionic acid, estersof 3,5-di-tert.-butyl-4-hydroxyphenylacetic acid, esters ofhydroxybenzylphosphonic acids, acylaminophenols or aromatic amines, UVabsorbers and light stabilisers such as2-(2'-hydroxyphenyl)-benzotriazoles, 2-hydroxybenzophenones,1,3-bis-(2'-hydroxybenzoyl)-benzenes, aryl esters of hydroxybenzoicacids, α-cyanocinnamic acid derivatives, nickel compounds or stericallyhindered amines or oxalic acid dianilides, metal deactivators,phosphites and phosphonites, compounds which destroy peroxides, basicco-stabilisers, PVC stabilisers, nucleating agents or other additives,for example plasticisers, lubricants, emulsifiers, fillers carbon black,asbestos, kaolin, talc, glass fibres, pigments, fluorescent brighteners,flameproofing agents and antistatic agents.

Examples of further additives together with which the stabilisers whichcan be used according to the invention can be employed are to be foundon pages 18-24 of German Offenlegungsschrift No. 2,427,853.

With the concomitant use of known stabilisers, synergistic effects canoccur, and this is frequently the case, especially with the concomitantuse of UV absorbers.

The polymers according to the invention can also be used in the form oftheir complexes with heavy metal compounds, in particular nickel orcobalt compounds. Examples of these are complexes with nickel acetate,nickel stearate or nickel acetylacetonate.

The examples which follow illustrate the preparation of the polymersaccording to the invention and their use as light stabilisers. Thetemperatures indicated therein are given in °C.

EXAMPLE 1

20.53 g (0.05 mol) ofbis-(1,2,2,6,6-pentamethyl-piperidin-4-yl)malonate, 13.19 g ofα,α'-dibromo-p-xylene (0.05 mol), 14.5 g (0.105 mol) of finely powderedanhydrous potassium carbonate, 0.66 g of 18-crown-6(1,4,7,10,13,16-hexaoxa-cyclooctadecane) and 1.6 g of polyethyleneglycol 400 are heated at 140° for 43 hours, with efficient stirring andunder a nitrogen atmosphere. For working-up, the cooled reaction melt istaken up in methylene chloride, the solution is filtered through a thinlayer of kieselguhr (Hyflo) until the filtrate is clear, and the solventis completely distilled off in vacuo. The residue is dissolved in 25 mlof butan-2-one and the solution is poured into 500 ml of water, withvigorous stirring, the polymeric compound precipitating out and thecrown ether and the polyethylene glycol 400 remaining dissolved in thewater. The aqueous phase is decanted, the polymeric precipitate isdissolved in methylene chloride and the solution is dried over sodiumsulfate and filtered. The methylene chloride solution is concentrated toabout 50-60 ml and the product is reprecipitated by pouring theconcentrate into 500 ml of methanol, with rapid stirring. Theprecipitated colourless polymer is dried in a high vacuum. It has asoftening point of about 110° and has the structure ##STR7## and anaverage molecular weight Mn of 10,300, which corresponds to an averagedegree of polycondensation m=20.

(C₃₁ H₄₈ N₂ O₄)_(m) calculated: N 5.46%. (512.67)_(m) found: N 5.3%.Bromine content: <0.1% of Br.

EXAMPLE 2

Analogously to Example 1, 20.53 g (0.05 mol) ofbis-(1,2,2,6,6-pentamethyl-piperidin-4-yl)malonate and 11.61 g ofα,α'-dibromo-p-xylene (0.044 mol), i.e. a molar ratio of about 9:8, arereacted with one another. This gives an oligomeric compound having asoftening point of ˜60° and an average molecular weight (Mn) of 2,000.This substance still had a residual bromine content of 0.8%. Thisresidual bromine was removed as follows:

14.6 g of the oligomeric compound with a low bromine content aredissolved in 50 ml of dioxane, the solution is treated with 2 ml of a 1N silver nitrate solution and the mixture is stirred at room temperaturefor 24 hours. The reaction solution is then filtered through a layer ofHyflo, the filtrate is freed of the dioxane in vacuo, the residue isdissolved in methylene chloride, the solution is washed four times with25 ml of water and the oligomer is precipitated by pouring the methylenechloride solution into 300 ml of acetonitrile. The oligomeric compoundthus obtained (formula cf. Example 1) is dried in a high vacuum. It isvirtually free of halogen (content <0.1% of Br) and has a softeningpoint of ˜95° and an average molecular weight (Mn) of 2,540.

EXAMPLE 3

41.1 g (0.1 mol) of bis-(1,2,2,6,6-pentamethylpiperidin-4-yl)malonate,21.9 g (0.09 mol) of 1,6-dibromohexane, 33.2 g (0.24 mol) of potassiumcarbonate, 1.32 g of 18-crown-6 and 1.67 g of tetrabutylammoniumbisulfate, in 100 ml of anhydrous xylene, are heated at 110° for 70hours, with sitrring and in a nitrogen atmosphere. The reaction mixtureis then filtered, the filtrate is washed with three times 50 ml ofwater, the organic phase is dried over sodium sulfate and the solvent isdistilled off in vacuo. The crude oligomeric compound is then furtherpurified by repeated precipitation: it is first precipitated from aconcentrated ethanol solution in 450 ml of ethanol/water (2:1 by volume)and then from a methylene chloride solution in 400 ml of acetonitrile,the liquid is decanted and the precipitated product is dried in a highvacuum. The oligomeric compound thus obtained has a softening point ofabout 60°, an average molecular weight (Mn) of 2,500 (corresponding tom=5) and a residual bromine content <0.1%. ##STR8##

(C₂₉ H₅₂ N₂ O₄)_(m) calculated: N 5.68%. (492.7)_(m) found: N 5.4%.

EXAMPLE 4

39.4 g (0.07 mol) ofbis-(1-benzyl-2,2,6,6-tetramethyl-piperidin-4-yl)malonate, 20.7 g (0.063mol) of 1,12-dibromododecane, 20.3 g of potassium carbonate, 0.93 g of18-crown-6 and 3 g of polyethylene glycol methyl ether (molecular weightabout 750) are heated at 130°-135° for 60 hours, with vigorous stirring.The reaction mixture, cooled to 80°, is then diluted withdichloroethane, the solution is filtered until the filtrate is clear,and the solvent is distilled off in vacuo. The residue is dissolved inabout 100 ml of butan-2-one, the solution is poured into 800 ml ofwater, with vigorous turbine-stirring, the liquid is decanted from theprecipitated product, the latter is dissolved in methylene chloride andthe solution is dried over sodium sulfate. After concentration to about100 ml, the methylene chloride solution is poured into 800 ml ofmethanol, with rapid stirring, the precipitated oligomer is separatedoff and washed with methanol and the compound thus obtained is dried ina high vacuum. It has a softening point of 50° and an average molecularweight (Mn) of 3,600, corresponding to an average degree ofpolycondensation m=5. The residual bromine content is <0.1%. ##STR9##

(C₄₇ H₇₂ N₂ O₄)_(m) calculated: N 3.84%. (729.1)_(m) found: N 4.1%.

EXAMPLES 5-15

The oligomeric compounds listed in Table 1 were prepared analogously toExamples 1 or 4.

                                      TABLE 1                                     __________________________________________________________________________    Homopolymeric products of the formula                                          ##STR10##                                                                    Example                                                                            R.sup.3           R.sup.4                                                                            T.sub.s *                                                                          --M.sub.n                                                                         Br content                               __________________________________________________________________________    5    (CH.sub.2).sub.6  H    ˜50°                                                                  3,500                                                                             <0.1%                                    6    (CH.sub.2).sub.6  Benzyl                                                                             ˜80°                                                                  2,080                                                                             <0.1%                                    7    (CH.sub.2).sub.4  CH.sub.3                                                                           ˜67°                                                                  1,740                                                                             0.7%                                     8    CH.sub.2 CHCHCH.sub.2                                                                           CH.sub.3                                                                           ˜75°-80°                                                       1,600                                                                             <0.3%                                      9                                                                                 ##STR11##        Benzyl                                                                             ˜110°                                                                 3,200                                                                             0.2%                                       10                                                                                ##STR12##        CH.sub.3                                                                           ˜130°                                                                 3,600                                                                             0.3%                                       11                                                                                ##STR13##        H    ˜190°                                                                 5,000                                                                             <0.1%                                      12 (CH.sub.2).sub.12 CH.sub.3                                                                           ˜20°                                                                  11,000                                                                            <0.1%                                                                (resin)                                             13                                                                                ##STR14##        COCH.sub.3                                                                         ˜30°                                                                  2,000                                                                             <0.1%                                      14 (CH.sub.2).sub.6  COCH.sub.3                                                                         ˜45°-50°                                                       3,100                                                                             <0.1%                                      15                                                                                ##STR15##        Allyl                                                                              ˜145°                                                                 2,020                                                                             <0.1%                                    __________________________________________________________________________     *softening temperature                                                   

EXAMPLES 16-18

Analogously to Example 1, 30.7 g (0.07 mol) ofbis-[2-(2,2,6,6-tetramethyl-piperidino)-ethyl]malonate are reacted with16.42 g (0.062 mol) of α,α-dibromo-p-xylene, an oligomer of the formula##STR16## being obtained which has a softening point of 72°-75° C. and abromine content of <0.1%. The average molecular weight Mn is 3,300.

The following were obtained analogously: ##STR17## Softening temperature(T_(s)) about 50°, Mn 2,100. ##STR18## Softening temperature (T_(s))68°, Mn 3,900.

EXAMPLES 19 AND 20

Analogously to Example 1, 0.1 mol ofN,N'-di-(1,2,2,6,6-pentamethylpiperidin-4-yl)-malonamide is reacted with0.1 mol of 1,8-dibromooctane to give the oligomer of the formula##STR19## and with 0.1 mol of p-xylylene dibromide to give the oligomerof the formula ##STR20##

EXAMPLES 21 AND 22

Analogously to Example 1, 0.06 mol of(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)cyanoacetate is reacted with0.06 mol of 1,12-dibromodecane to give the oligomer of the formula##STR21##

The oligomer of the formula ##STR22## is obtained analogously from(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)ethyl malonate, and1,12-dibromododecane.

EXAMPLES 23 AND 24

Analogously to Example 1, a mixture of 0.02 mol ofbis-(1,2,2,6,6-pentamethylpiperidin-4-yl)malonate and 0.04 mol ofbis-(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)malonate is reacted with0.06 mol of 1,6-dibromohexane. This gives an oligomer of the formula##STR23## in which R=benzyl, with a ratio m:n=0.5. It has a softeningpoint of 74° and an average molecular weight (Mn) of 2,450. The residualbromine content is <0.3%.

An oligomer of the above formula in which R=allyl and the ratio m:n=2 isobtained analogously from 0.04 mol ofbis-(1,2,2,6,6-pentamethylpiperidin-4-yl)malonate and 0.02 mol ofbis-(1-allyl-2,2,6,6-tetramethylpiperidin-4-yl)malonate. T_(s) 25°, Mn4,300 (Example 24).

EXAMPLE 25

An oligomer with three different molecular units is obtained by thepolycondensation of a mixture of 0.04 mol ofbis-(1,2,2,6,6-pentamethylpiperidin-4-yl)malonate, 0.04 mol ofbis-(1-allyl-2,2,6,6-tetramethylpiperidin-4-yl)malonate and 0.04 mol ofbis-(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)malonate with 0.12 molof 1,6-dibromohexane.

The product corresponds to the formula ##STR24## and has a softeningpoint of 74° and an average molecular weight Mn of 3,900.

EXAMPLE 26

An ester-amide copolymer is obtained by the polycondensation of amixture of 0.05 mol of bis-(1,2,2,6,6-pentamethylpiperidin-4-yl)malonateand 0.05 mol of N,N'-di-(1,2,2,6,6-pentamethylpiperidin-4-yl)malonatewith 0.1 mol of 1,6-dibromohexane by the method described in Example 1.

The product corresponds to the formula ##STR25## and has a softeningpoint of 115° and an Mn of 3,050.

EXAMPLES 27 AND 28

112.5 g (0.7 mol) of diethyl malonate, 151.3 g (0.63 mol) of1,6-dibromohexane, 203 g of finely powdered anhydrous potassiumcarbonate, 4 g of 18-crown-6 and 7.5 g of distilled polyethylene glycoldimethyl ether (Mn ≈500) are heated at 130° C. for 35 hours, withefficient stirring (anchor stirrer made of V₄ A stainless steel) andunder an N₂ atmosphere. For working-up, the virtually colourlessreaction melt is diluted with methylene chloride, after cooling, thesolution is filtered until the filtrate is clear, and the solvent iscompletely distilled off in vacuo. The residue is dissolved in about 100ml of diethyl ether and the solution is poured slowly into 1 liter ofn-hexane, with vigorous turbine-stirring. The precipitated oilyoligomeric malonic acid ester is separated off, washed with hexane andcompletely freed of the solvent in a high vacuum. The oligomeric diethylmalonate thus obtained, which has the structure ##STR26## is a lightyellow oil and has an Mn of 1,450, which corresponds to an averagedegree of polycondensation m=6. The ¹³ C NMR spectrum corresponds to thestructure shown.

10.9 g of this product are transesterified with 22.3 g of1-benzyl-2,2,6,6-tetramethylpiperidin-4-ol in 300 ml of xylene, in thepresence of 0.2 ml of tetrabutyl orthotitanate as a catalyst, withstirring, in a gentle N₂ stream, at 130°-145°, the ethanol which hasbeen split off, together with some xylene, being distilled offcontinuously through the descending condenser over 24 hours. After thetransesterification has ended, the reaction mixture is dissolved in asmall amount of methylene chloride and the solution is poured slowlyinto 500 ml of methaol, with vigorous turbine-stirring, at 0°, wherebythe oligomeric ester is precipitated. The methanol is separated off andthe precipitate is washed with fresh methanol and completely dried in ahigh vacuum at about 40° C. The oligomeric ester thus obtained, whichhas the formula ##STR27## has a softening point of about 70° and an Mnof 2,400. Its properties are similar to those of the product of Example6, which has the same structure.

A product of the formula ##STR28## which has a softening point of 30°and an Mn of 3,200 (Example 28), was prepared analogously from theoligomeric diethyl malonate by reaction with1-allyl-2,2,6,6-piperidin-4-ol.

EXAMPLE 29 LIGHT STABILISATION OF POLYPROPYLENE

100 parts of polypropylene powder (Moplen, Fibre grade, from Montedison)are homogenised with 0.2 part of octadecylβ-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionate, 0.1 part of calciumstearate and 0.25 part of a light stabiliser from Table 2 below, in aBrabender Plastograph, at 200° C., for 10 minutes. The composition thusobtained is removed from the kneader as quickly as possible andcompressed in a toggle press to form a 2-3 mm thick plate. Part of theblank obtained is cut out and compressed between two highly polishedhard aluminium foils with a hydraulic laboratory hand-press, for 6minutes, at 260° C., to form a 0.1 mm thick film, which is immediatelyquenched in cold water. Sections are the stamped out of this film andexposed in a Xenotest 1200. At regular intervals of time, thesetest-pieces are removed from the exposure apparatus and tested in an IRspectrophotometer for their carbonyl content. The increase in thecarbonyl extinction at 5.85 μm during exposure is a measure of thephotooxidative degradation of the polymer (cf. L. Balaban et al., J.Polymer Sci., Part C; 22, 1,059-1,071 (1969)) and experience shows thatit is related to the deterioration in the mechanical properties of thepolymer. The time taken to reach a carbonyl extinction of about 0.3, atwhich the film is brittle, is a measure of the stabilising action. For acomparison film not containing light stabiliser, this exposure time isabout 900 hours.

    ______________________________________                                        Light stabiliser                                                                             Exposure time                                                  Example No.    in hours                                                       ______________________________________                                        1               3,660                                                         2              >5,500                                                         3               5,000                                                         4              >4,600                                                         5               4,490                                                         6               5,450                                                         7              >5,300                                                         8              >4,600                                                         9               4,130                                                         10              2,430                                                         11             >4,300                                                         12             >4,400                                                         13              3,200                                                         14             >4,200                                                         15             >4,200                                                         16             >4,400                                                         17             >4,200                                                         20             >3,000                                                         24             >3,000                                                         28             >3,200                                                         ______________________________________                                    

What is claimed is:
 1. A polymer or oligomeric compound of the generalformula I ##STR29## and its salts, in which X is --CO--Y--R² or --CN,X^(a) is --CO--Y^(a) --R^(2a) or --CN, and X^(b) is --CO--Y^(b) --R^(2b)or --CN, Y, Y^(a) and Y^(b) independently of one another are --O-- or--NR¹⁰ --, R¹, R^(1a) and R^(1b) independently of one another are agroup of the formulae II, III, IV, V or VI ##STR30## and R^(1a) is alsoC₁ -C₁₈ -alkyl, R² is identical to R¹ or is H, C₁ -C₁₈ -alkyl, C₃ -C₇-alkenyl or C₇ -C₁₁ -aralkyl, R^(2a) is identical to R^(1a) or is H, C₁-C₁₈ -alkyl, C₃ -C₇ -alkenyl or C₇ -C₁₁ -aralkyl, and R^(2b) isidentical to R^(1b) or is H, C₁ -C₁₈ -alkyl, C₃ -C₇ -alkenyl or C₇ -C₁₁-aralkyl, R³, R^(3a) and R^(3b) independently of one another are C₂ -C₃₆-alkylene, C₄ -C₁₈ -alkenylene, C₈ -C₂₀ -arylene-dialkylene, C₈ -C₁₂-cycloalkylene-dialkylene or C₄ -C₂₀ -monooxa-alkylene orpolyoxa-alkylene, R⁴ is hydrogen, C₁ -C₁₈ -alkyl, C₃ -C₁₈ -alkenyl, C₃-C₅ -alkynyl, C₂ -C₁₈ -alkanoyl, C₃ -C₅ -alkenoyl, benzoyl,unsubstituted or C₁ -C₄ -alkyl-substituted C₇ -C₁₁ -aralkyl,cyanomethyl, a group --CH₂ --CH(OH)--R⁶, OH, O.(oxyl oxygen), --COOC₁-C₄ -alkyl or --CON(R¹²) (R¹³), R⁵ is hydrogen or C₁ -C₄ -alkyl, R.sup.6 is hydrogen, C₁ -C₄ -alkyl, phenyl, C₁ -C₄ -alkoxy-methyl,phenoxymethyl or C₁ -C₄ -alkyl-phenoxymethyl, R⁷ is hydrogen, C₁ -C₁₈-alkyl, C₃ -C₁₈ -alkenyl, C₃ -C₅ -alkynyl, C₂ -C₁₈ -alkanoyl, C₃ -C₅-alkenoyl, unsubstituted or C₁ -C₄ -alkyl-substituted C₇ -C₁₁ -aralkyl,O. or cyanomethyl, R⁸ is C₁ -C₁₈ -alkyl, C₃ -C₁₈ -alkenyl, C₃ -C₅-alkynyl or C₇ -C₁₁ -aralkyl, R⁹ has one of the definitions given forR⁷, R¹⁰ is hydrogen, C₁ -C₁₈ -alkyl, C₃ -C₁₂ -alkenyl, cyclohexyl orunsubstituted or C₁ -C₄ -alkyl-substituted C₇ -C₁₁ -aralkyl or C₆ -C₁₂-aryl, R¹¹ is hydrogen or C₁ -C₄ -alkyl, R¹² is C₁ -C₁₂ -alkyl, C₃ -C₅-alkenyl, C₅ -C₈ -cycloalkyl, phenyl or benzyl, and R¹³ is hydrogen, C₁-C₁₂ -alkyl, C₃ -C₅ -alkenyl, C₅ -C₈ -cycloalkyl or benzyl, or R¹² andR¹³, together with the N atom to which they are bonded, form a5-7-membered heterocyclic ring, m, n and o independently of one anotherare zero or a number from 1 to 100, the sum of m+n+o being at least 3,and p is zero or
 1. 2. A compound, according to claim 1, of the formulaI in which m and n are zero or a number from 1 to 30 and o is zero, thesum of m+n being at least 3, X is --CO--Y--R² and X^(a) is --CO--Y^(a)--R^(2a), Y and Y^(a) are --O-- or --NR¹⁰ --, R¹ and R^(1a) are a groupof the formula II, III, IV or V and R^(1a) is also C₁ -C₈ -alkyl, R² isidentical to R¹ or is C₁ -C₆ -alkyl, and R^(2a) is identical to R^(1a)or is C₁ -C₆ -alkyl, R³ and R^(3a) are C₂ -C₁₈ -alkylene, C₄ -C₁₂-alkenylene, C₈ -C₁₇ -arylenedialkylene, C₈ -C₁₀-cycloalkylene-dialkylene or C₄ -C₈ -monooxaalkylene or C₄ -C₈-polyoxaalkylene, R⁴ is hydrogen, C₁ -C₆ -alkyl, C₃ -C₅ -alkenyl,propargyl, C₂ -C₅ -alkanoyl, C₃ -C₅ -alkenoyl or C₇ -C₁₁ -aralkyl, R⁵ ishydrogen, R⁶ is hydrogen, C₁ -C₂ -alkyl, phenyl or phenoxymethyl, R⁷ hasone of the definitions given for R⁴, R⁸ is C₁ -C₁₂ -alkyl, c₃ -C₅-alkenyl or C₇ -C₁₁ -aralkyl, R⁹ has one of the definitions given forR⁴, and R¹⁰ is hydrogen, C₁ -C₁₂ -alkyl, benzyl or cyclohexyl.
 3. Acompound, according to claim 2, of the formula I in which m is 3-20, nand o are zero, R¹ and R² are a group of the formula II, R³ is C₆ -C₁₂-alkylene, 1,4-but-2-enylene, xylylene or cyclohexane-dimethylene, R⁴ ishydrogen, C₁ -C₄ -alkyl, allyl, benzyl or acetyl, and X, Y, R⁵ and R¹⁰are as defined in claim
 2. 4. An organic polymer stabilised againstdamage by the action of light, containing, as the light stabiliser, 0.01to 5% by weight, preferably 0.1 to 2% by weight, of a compound of theformula I, according to claim 1.